The Possible Plumes of Europa

Posted in The Universe and Stuff with tags , , , , , , , on September 27, 2016 by telescoper

I was too busy yesterday to write a post about the latest hot news from the NASA Hubble Space Telescope, so here’s a quick catch-up.

It seems that Europa, the smallest of the four Galilean moons of Jupiter, may from time to time be releasing “plumes” of water vapour. It has long been speculated that there might be large quantities of liquid water under Europa’s extremely smooth icy crust. Here’s a picture of possible plumes (to the bottom left of the image) in which a high-resolution picture of the surface of Europa has been superimposed.

europa

Picture Credits: NASA/ESA/W. Sparks (STScI)/USGS Astrogeology Science Center

There’s also short video explaining the possible discovery here.

It’s not obvious at first sight that features like that shown above are caused by water erupting through Europa’s surface. On the face of it they could, for example, be caused by the impact of a smaller body. However,  long-term observations of this phenomenon suggest out-gassing is much more likely.  The Hubble Space Telescope’s Imaging Spectrograph was used to study what are essentially Aurorae powered by Jupiter’s strong magnetic field in which the presence of excited states of hydrogen and oxygen provide evidence for the disintegration of water molecules through interaction with electrons in this highly energetic environment. The images were taken when Europa was in front of Jupiter so they are seen were seen in silhouette.

There is also evidence that these appearance of these plumes is periodic, and that they are more likely to occur when Europa is further from Jupiter than when it is closer. A plausible theory is that water is released from cracks in Europa’s surface which open and close owing to a combination of tidal gravitational and magnetic effects.

I wouldn’t say this was definite proof of the water interpretation. These observations push the capability of the Hubble Space Telescope to the limit because the features are so faint. For information here’s what the raw image looks like (left)  and with enhanced contrast (right):

raw_image

 

Verification of these results through independent means is clearly an important priority, though likely to prove challenging. The plume interpretation is possible, but whether it is yet probable I couldn’t say!

 

 

My First Contribution to the Scientific Literature.

Posted in Biographical, The Universe and Stuff on September 26, 2016 by telescoper

I suddenly realized yesterday that I had forgotten to mark the important anniversary of an event that had immense impact on the field of cosmology. On 15th September 1986, just over thirty years ago, my first ever scientific paper was released into the public domain.

Here is the front page:

mnras_paper

This was before the days of arXiv so there isn’t a copy on the preprint server, but you can access the whole article here on NASA/ADS.

I know it’s a shitty little paper, but you have to start somewhere! I’m particularly sad that, looking back, it reads as if I meant to be very critical of the Kaiser (1984) paper that inspired it. I still think that was a brilliant paper because it was based on a very original idea that proved to be enormously influential. The only point I was really making was that a full calculation of the size of the effect Nick Kaiser had correctly identified was actually quite hard, and his simple approximation was of limited quantitative usefulness. The idea was most definitely right, however.

I was just a year into my PhD  DPhil when this paper came out, and it wasn’t actually on what was meant to be the subject of my thesis work (which was the cosmic microwave background), although the material was related. My original version of this paper had my supervisor’s name on it, but he removed his name from the draft (as well as making a huge number of improvements to the text). At the time I naturally assumed that he took his name off because he didn’t want to be associated with such an insignificant paper, but I later realized he was just being generous. It was very good for me to have a sole-author paper very early on. I’ve taken that lesson to heart and have never insisted – like some supervisors do – in putting my name on my students’ work.

Seeing this again after such a long time brought back memories of the tedious job of making and distributing hard copies of preprints when I submitted the paper and sending them by snail mail to prominent individuals and institutions. Everyone did that in those days as email was too limited to send large papers. Nowadays we just shove our papers on the arXiv, complete with fancy graphics, and save ourselves a lot of time and effort.

I was actually surprised that quite a few recipients of my magnum opus were kind enough to respond in writing. In particular I got a nice letter from Dick Bond which began by referring to my “anti-Kaiser” preprint, which made me think he was going to have a go at me, but went on to say that he found my paper interesting and that my conclusions were correct. I was chuffed by that letter as I admired Dick Bond enormously (and still do).

Anyway, over the intervening 30 years this paper has received the princely total of 22 citations -and it hasn’t been cited at all since 2000 – so its scientific impact hardly been earth-shattering. The field has moved on quickly and left this little relic far behind. However, there is one citation I am proud of.

The great Russian scientist Yacob Borisovich Zel’dovich passed away in 1987. I was a graduate student at that time and had never had the opportunity to meet him. If I had done so I’m sure I would have found him fascinating and intimidating in equal measure, as I admired his work enormously as did everyone I knew in the field of cosmology. Anyway, a couple of years after his death a review paper written by himself and Sergei Shandarin was published, along with the note:

The Russian version of this review was finished in the summer of 1987. By the tragic death of Ya. B.Zeldovich on December 2, 1987, about four-fifths of the paper had been translated into English. Professor Zeldovich would have been 75 years old on March 8, 1989 and was vivid and creative until his last day. The theory of the structure of the universe was one of his favorite subjects, to which he made many note-worthy contributions over the last 20 years.

As one does if one is vain I looked down the reference list to see if any of my papers were cited. I’d only published the one paper before Zel’dovich died so my hopes weren’t high. As it happens, though, my very first paper (Coles 1986) was there in the list:

reference

Sonnet No. 73

Posted in Uncategorized on September 24, 2016 by telescoper

That time of year thou may’st in me behold 
When yellow leaves, or none, or few, do hang
Upon those boughs which shake against the cold, 
Bare ruin’d choirs, where late the sweet birds sang. 
In me thou see’st the twilight of such day, 
As after sunset fadeth in the west, 
Which by-and-by black night doth take away,
Death’s second self, that seals up all in rest. 
In me thou see’st the glowing of such fire 
That on the ashes of his youth doth lie, 
As the death-bed whereon it must expire 
Consum’d with that which it was nourish’d by. 
   This thou perceivest, which makes thy love more strong,
   To love that well which thou must leave ere long.

by William Shakespeare (1564-1616)

The Worthless University Rankings

Posted in Bad Statistics, Education with tags , , , on September 23, 2016 by telescoper

The Times Higher World University Rankings, which were released this weekk. The main table can be found here and the methodology used to concoct them here.

Here I wish to reiterate the objection I made last year to the way these tables are manipulated year on year to create an artificial “churn” that renders them unreliable and impossible to interpret in an objective way. In other words, they’re worthless. This year, editor Phil Baty has written an article entitled Standing still is not an option in which he makes a statement that “the overall rankings methodology is the same as last year”. Actually it isn’t. In the page on methodology you will find this:

In 2015-16, we excluded papers with more than 1,000 authors because they were having a disproportionate impact on the citation scores of a small number of universities. This year, we have designed a method for reincorporating these papers. Working with Elsevier, we have developed a new fractional counting approach that ensures that all universities where academics are authors of these papers will receive at least 5 per cent of the value of the paper, and where those that provide the most contributors to the paper receive a proportionately larger contribution.

So the methodology just isn’t “the same as last year”. In fact every year that I’ve seen these rankings there’s been some change in methodology. The change above at least attempts to improve on the absurd decision taken last year to eliminate from the citation count any papers arising from large collaborations. In my view, membership of large world-wide collaborations is in itself an indicator of international research excellence, and such papers should if anything be given greater not lesser weight. But whether you agree with the motivation for the change or not is beside the point.

The real question is how can we be sure that any change in league table position for an institution from year to year are is caused by methodological tweaks rather than changes in “performance”, i.e. not by changes in the metrics but by changes in the way they are combined? Would you trust the outcome of a medical trial in which the response of two groups of patients (e.g. one given medication and the other placebo) were assessed with two different measurement techniques?

There is an obvious and easy way to test for the size of this effect, which is to construct a parallel set of league tables, with this year’s input data but last year’s methodology, which would make it easy to isolate changes in methodology from changes in the performance indicators. The Times Higher – along with other purveyors of similar statistical twaddle – refuses to do this. No scientifically literate person would accept the result of this kind of study unless the systematic effects can be shown to be under control. There is a very easy way for the Times Higher to address this question: all they need to do is publish a set of league tables using, say, the 2015/16 methodology and the 2016/17 data, for comparison with those constructed using this year’s methodology on the 2016/17 data. Any differences between these two tables will give a clear indication of the reliability (or otherwise) of the rankings.

I challenged the Times Higher to do this last year, and they refused. You can draw your own conclusions about why.

End of Summer, Start of Autumn

Posted in Biographical, Cricket with tags , , , on September 22, 2016 by telescoper

It’s a lovely warm sunny day in Cardiff today, but it is nevertheless the end of summer. The autumnal equinox came and went today (22nd September) at 14.21 Universal Time (that’s 15.21 British Summer Time), so from now on it’s all downhill (in that the Subsolar point has just crossed the equator on the southward journey it began at the Summer Solstice).

Many people adopt the autumnal equinox as the official start of autumn, but I go for an alternative criterion: summer is over when the County Championship is over. It turns out that, at least for Glamorgan, that coincided very closely to the equinox. Having bowled out Leicestershire for a paltry 96 at Grace Road in the first innings of their final Division 2 match, they went on to establish a handy first-innings lead of 103. They were then set a modest second-innings target of 181 to win. Unfortunately, their batting frailties were once again cruelly exposed and they collapsed from 144 for 4 to 154 all out and lost by 26 runs. That abject batting display sums up their season really.

Meanwhile, in Division 1 of the Championship, Middlesex are playing Yorkshire at Lord’s, a match whose outcome will determine who wins the Championship. Middlesex only need to draw to be champions, but as I write they’ve just lost an early wicket in their second innings, with Yorkshire having a first-innings lead of 120, so it’s by no means out of the question that Yorkshire might win and be champions again.

Another sign that summer is over is that the new cohort of students has arrived. This being “Freshers’ Week” there have been numerous events arranged to introduce them to various aspects of university life. Lectures proper being in Monday, when the Autumn Semester begins in earnest. I don’t have any teaching until the Spring.

This time of year always reminds me when I left home to go to University, as thousands of fledgling students have just done. I went through this rite of passage 34 years ago, getting on a train at Newcastle Central station with my bags of books and clothes. I said goodbye to my parents there. There was never any question of them taking me in the car all the way to Cambridge. It wasn’t practical and I wouldn’t have wanted them to do it anyway. After changing from the Inter City at Peterborough onto a local train, me and my luggage trundled through the flatness of East Anglia until it reached Cambridge.

I don’t remember much about the actual journey, but I must have felt a mixture of fear and excitement. Nobody in my family had ever been to University before, let alone to Cambridge. Come to think of it, nobody from my family has done so since either. I was a bit worried about whether the course I would take in Natural Sciences would turn out to be very difficult, but I think my main concern was how I would fit in generally.

I had been working between leaving school and starting my undergraduate course, so I had some money in the bank and I was also to receive a full grant. I wasn’t really worried about cash. But I hadn’t come from a posh family and didn’t really know the form. I didn’t have much experience of life outside the North East either. I’d been to London only once before going to Cambridge, and had never been abroad.

I didn’t have any posh clothes, a deficiency I thought would mark me as an outsider. I had always been grateful for having to wear a school uniform (which was bought with vouchers from the Council) because it meant that I dressed the same as the other kids at School, most of whom came from much wealthier families. But this turned out not to matter at all. Regardless of their family background, students were generally a mixture of shabby and fashionable, like they are today. Physics students in particular didn’t even bother with the fashionable bit. Although I didn’t have a proper dinner jacket for the Matriculation Dinner, held for all the new undergraduates, nobody said anything about my dark suit which I was told would be acceptable as long as it was a “lounge suit”. Whatever that is.

Taking a taxi from Cambridge station, I finally arrived at Magdalene College. I waited outside, a bundle of nerves, before entering the Porter’s Lodge and starting my life as a student. My name was found and ticked off and a key issued for my room in the Lutyens building. It turned out to be a large room, with a kind of screen that could be pulled across to divide the room into two, although I never actually used this contraption. There was a single bed and a kind of cupboard containing a sink and a mirror in the bit that could be hidden by the screen. The rest of the room contained a sofa, a table, a desk, and various chairs, all of them quite old but solidly made. Outside my  room, on the landing, was the gyp room, a kind of small kitchen, where I was to make countless cups of tea over the following months, although I never actually cooked anything there.

I struggled in with my bags and sat on the bed. It wasn’t at all like I had imagined. I realised that no amount of imagining would ever really have prepared me for what was going to happen at University.

I  stared at my luggage. I suddenly felt like I had landed on a strange island, and couldn’t remember why I had gone there or what I was supposed to be doing.

After 34 years you get used to that feeling…

 

The Byker Grove Connection

Posted in Biographical, History, Television with tags , , , on September 21, 2016 by telescoper

One of the interesting things about having a blog that has been running for some time is that old posts continue to attract comments even after many years. Some of the posts that have been getting comments recently are about my early childhood growing up in Benwell which is to the West of Newcastle upon Tyne; you can find a couple of examples here and here. The place has changed beyond all recognition since I was a kid, which I suppose accounts for the fact that people are googling about looking for memories of what it used to be like.

Here is a Google Earth rendition of the area I grew up in..

benwell

We used to live in one of the two cottages right next to Pendower School, which was just off Fox and Hounds Lane.  You can see road that led to the front of our house, just between the text of “Benwell Village” and “Fox and Hounds Lane”.  The cottages and school are now demolished, and a housing development stands where they were. That’s all in the middle of the top of the image.

My Dad used to run a  shop which was was on the corner of Whickham View and Delaval Road, about halfway down the image to the left. The green strips to the East of Delaval Road and running parallel to it were all terraced when I lived there. Virtually everything has now gone, but it was a nice little community with old-fashioned little shops.

What drew my attention recently however, is that there is a location (to the top left of the image) marked Byker Grove., right next to where I used to live. When I was a lad that was  Benwell Towers, which we were told was haunted – presumably to scare us off trying to get in. There was a rather scary and formidable fence separating the grounds of Benwell Towers from the School, but it was not unknown for kids to climb it…

There have been buildings on the site of Benwell Towers since the 13th Century. A tower house was built there in 1221 and stood until it was demolished to make way for the current, much larger, building which was constructed in 1831. The old building was for a time owned by a branch of the Shafto family, of Bobby Shafto fame. At the time of the construction of the new building, Benwell hadn’t been engulfed by the westward sprawl of Newcastle itself and was very much a separate village. “Benwell Village” still felt like a distinct, self-contained community, when I was growing up there in the Sixties.

The “new” Benwell Towers was, for a time, the residence of the Bishop of Newcastle, but when I lived there it was being used as a base for the National Coal Board and used primarily as the Headquarters  of the Mine Rescue Service. There were some pits still open in those days.  When the Coal Board didn’t need it any more, it became a tacky nightclub called The Mitre

That’s all I knew about the place as I never really visited it again after going to University . But a chance comment on this blog followed by a Google Search revealed that when The Mitre closed the building was used to film the long-running TV series Byker GroveI knew about the programme, but had always assumed it was filmed in Byker (which is in the East End of Newcastle) rather than Benwell (which is in the West End). It certainly never occurred to me that it was made just a hundred yards from where I grew up. You live and learn.

 

 

Jazz Samba – Bill Evans & Jim Hall

Posted in Jazz with tags , , , on September 21, 2016 by telescoper

A couple of weeks ago I posted an item about a classic recording of On Green Dolphin Street featuring the great pianist Bill Evans. At the weekend I was listening to some CDs from my collection and thought I’d post a track from one of them, an album called Intermodulation (recorded in 1966) which features Bill Evans in collaboration with the guitarist Jim Hall. One of the notable things about Bill Evans’s On Green Dolphin Street was the “two-handedness” of his playing which gives his improvisations a very rich harmonic structure. In this recording, however, apart from the introduction and ending he uses practically only his right hand. The reason for this change in style is simple: he wanted to leave space for Jim Hall’s guitar chords to be heard. Anyway, it’s a lovely piece with a real sense of dance to it, and in which the pairing of these two great musicians is heard to great combined effect. Enjoy!